1,633 research outputs found
Experimental investigation of reactor-loop transients during startup of a simulated SNAP-8 system
Primary loop transients during startup of Rankine cycle space power system in SNAP 8 simulato
Expression patterns of chondrocyte genes cloned by differential display in tibial dyschondroplasia
AbstractTibial dyschondroplasia (TD) appears to involve a failure of the growth plate chondrocytes within growing long bones to differentiate fully to the hypertrophic stage, resulting in a mass of prehypertrophic chondrocytes which form the avascular TD lesion. Many biochemical and molecular markers of chondrocyte hypertrophy are absent from the lesion, or show reduced expression, but the cause of the disorder remains to be identified. As differentiation to the hypertrophic state is impaired in TD, we hypothesised that chondrocyte genes that are differentially expressed in the growth plate should show altered expression in TD. Using differential display, four genes, B-cadherin, EF2, HT7 and Ex-FABP were cloned from chondrocytes stimulated to differentiate to the hypertrophic stage in vitro, and their differential expression confirmed in vivo. Using semi-quantitative RT-PCR, the expression patterns of these genes were compared in chondrocytes from normal and TD growth plates. Surprisingly, none of these genes showed the pattern of expression that might be expected in TD lesion chondrocytes, and two of them, B-cadherin and Ex-FABP, were upregulated in the lesion. This indicates that the TD phenotype does not merely reflect the absence of hypertrophic marker genes, but may be influenced by more complex developmental mechanisms/defects than previously thought
Multiplpe Choice Minority Game With Different Publicly Known Histories
In the standard Minority Game, players use historical minority choices as the
sole public information to pick one out of the two alternatives. However,
publishing historical minority choices is not the only way to present global
system information to players when more than two alternatives are available.
Thus, it is instructive to study the dynamics and cooperative behaviors of this
extended game as a function of the global information provided. We numerically
find that although the system dynamics depends on the kind of public
information given to the players, the degree of cooperation follows the same
trend as that of the standard Minority Game. We also explain most of our
findings by the crowd-anticrowd theory.Comment: Extensively revised, to appear in New J Phys, 7 pages with 4 figure
The optical flare
Optical observationd now present considerable information on the flare process. It is always associated with filaments and with simplification of existing magnetic connections, and it arises from the emergence and expansion of new flux.
The optical flare divides into impulsive phase, with multiple flashes along the neutral line, and thermal phase, with two-ribbon expansion. The former bears some resemblance to tearing mode phenomena.
The appearance of loops in emission requires very high densities in those phenomena.
The ratios of the hydrogen lines, the excitation of HeII 4686, and the relation of vertical to horizontal structure all remain to be explained
Wave Propagation and Jet Formation in the Chromosphere
We present the results of numerical simulations of wave propagation and jet
formation in solar atmosphere models with different magnetic field
configurations. The presence in the chromosphere of waves with periods longer
than the acoustic cutoff period has been ascribed to either strong inclined
magnetic fields, or changes in the radiative relaxation time. Our simulations
include a sophisticated treatment of radiative losses, as well as fields with
different strengths and inclinations. Using Fourier and wavelet analysis
techniques, we investigate the periodicity of the waves that travel through the
chromosphere. We find that the velocity signal is dominated by waves with
periods around 5 minutes in regions of strong, inclined field, including at the
edges of strong flux tubes where the field expands, whereas 3-minute waves
dominate in regions of weak or vertically oriented fields. Our results show
that the field inclination is very important for long-period wave propagation,
whereas variations in the radiative relaxation time have little effect.
Furthermore, we find that atmospheric conditions can vary significantly on
timescales of a few minutes, meaning that a Fourier analysis of wave
propagation can be misleading. Wavelet techniques take variations with time
into account and are more suitable analysis tools. Finally, we investigate the
properties of jets formed by the propagating waves once they reach the
transition region, and find systematic differences between the jets in inclined
field regions and those in vertical field regions, in agreement with
observations of dynamic fibrils.Comment: 27 pages, 29 figures; accepted for publication in Astrophysical
Journa
Type 1 Diabetes Mellitus-Associated Genetic Variants Contribute to Overlapping Immune Regulatory Networks
Type 1 diabetes (T1D) is a chronic metabolic disorder characterized by the autoimmune destruction of insulin-producing pancreatic islet beta cells in genetically predisposed individuals. Genome-wide association studies (GWAS) have identified over 60 risk regions across the human genome, marked by single nucleotide polymorphisms (SNPs), which confer genetic predisposition to T1D. There is increasing evidence that disease-associated SNPs can alter gene expression through spatial interactions that involve distal loci, in a tissue- and development-specific manner. Here, we used three-dimensional (3D) genome organization data to identify genes that physically co-localized with DNA regions that contained T1D-associated SNPs in the nucleus. Analysis of these SNP-gene pairs using the Genotype-Tissue Expression database identified a subset of SNPs that significantly affected gene expression. We identified 246 spatially regulated genes including HLA-DRB1, LAT, MICA, BTN3A2, CTLA4, CD226, NOTCH1, TRIM26, PTEN, TYK2, CTSH, and FLRT3, which exhibit tissue-specific effects in multiple tissues. We observed that the T1D-associated variants interconnect through networks that form part of the immune regulatory pathways, including immune-cell activation, cytokine signaling, and programmed cell death protein-1 (PD-1). Our results implicate T1D-associated variants in tissue and cell-type specific regulatory networks that contribute to pancreatic beta cell inflammation and destruction, adaptive immune signaling, and immune-cell proliferation and activation. A number of other regulatory changes we identified are not typically considered to be central to the pathology of T1D. Collectively, our data represent a novel resource for the hypothesis-driven development of diagnostic, prognostic, and therapeutic interventions in T1D
Theory of Networked Minority Games based on Strategy Pattern Dynamics
We formulate a theory of agent-based models in which agents compete to be in
a winning group. The agents may be part of a network or not, and the winning
group may be a minority group or not. The novel feature of the present
formalism is its focus on the dynamical pattern of strategy rankings, and its
careful treatment of the strategy ties which arise during the system's temporal
evolution. We apply it to the Minority Game (MG) with connected populations.
Expressions for the mean success rate among the agents and for the mean success
rate for agents with neighbors are derived. We also use the theory to
estimate the value of connectivity above which the Binary-Agent-Resource
system with high resource level goes into the high-connectivity state.Comment: 24 pages, 3 figures, submitted to PR
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